Plunger and screen for hydraulic underreamers



Nov. 20, 1934. 7 Q E, T 1,981,262

I PLUNGER AND SCREEN FORHYDRAULIC UNDERREAMERS Filed June 7, 1935 Patented Nov. 20, 1934 UNITED STATES PATENT OFFICE PLUNGER AND SCREEN FOR HYDRAULIC UNDEBBEAllEB-S Clarence E. Burt,

Baker Oil Tools, Inc.,

Los Angcles, cant, assignor a Huntington Park, CaliL,

a corporationof California Application June 7, 1933, Serial No. 6'l4,654

1 Claim.

The underreamer disclosed in the said Letters Patent is one in which a pair of reaming blades are pivoted for swinging movement through a transverse socket formed in a hollow barrel. Links connect the blades to a plunger rod, which rod depends from a plunger reciprocable in the barrel so that the blades may be swung into and out of the barrel by reciprocation of the plunger.

The present invention pertains to the construction of the plunger and to a screen member carried by the plunger to screen the lubricating fluid that is pumped through the plunger rod, said rod being formed with an axial bore for this purpose to lubricate the blades as they perform their reaming action.

It is the object of the present invention to provide a plunger for a hydraulic underreamer that is simpler in construction and more effective in operation than plungers heretofore used for this purpose and to provide a screen on said plunger that is so constructed that it will also serve as a wrench by means of which the plunger may be handled during assembly of the device.

One form which the invention may assume is exemplified in the following description and illusstrated by way of example in the accompanying drawing, in which:

Fig. 1 is a central vertical section of an underreamer barrel provided with a plunger and screen constructed in accordance with my invention;

Fig. 2 is a central vertical section of the plunger and strainer illustrated in Fig. 1.

Fig. 3 is a section taken on the line III--III of Fi 2.

Referring more particularly to the drawing, an underreamer barrel is illustrated at 10 and is provided with a transverse socket 11 for the reception of a pair of reamer blades 12 mounted for pivotal movement upon a hinge pin 13. Links indicated at 14 connect the blades 12 with a plunger rod 15 so that vertical reciprocation of the plunger rod will cause the reamer blades to be extended and retracted with relation to the barrel.

- The upper end of the plunger rod 15 is fitted with a plunger 16 and a strainer 1'7 is carried by and extends upwardly from the plunger. An expansible coil spring 18 disposed beneath the plunger 16 normally urges the plunger upwardly and the plunger may be forced downwardly against the tension of the spring 18 by means of fluid pressure in the barrel above it.

The construction of the plunger is shown in Figs. 2 and 3, in which figures it is illustrated as comprising a cylindrical sleeve 19 formed of cast bronze or other suitable durable material around which is fitted a molded rubber packing member 20. The lower end of the bronze sleeve 19 is provided with an outwardly extending annular shoulder 21, the outer periphery of which slidably fits the interior of the underreamer barrel. Extending upwardly from the flange 21 and spaced about the periphery of the sleeve 19 are integrally formed ribs 22 as illustrated in Fig. 3, said ribs being undercut along their edges so that when the rubber position about the sleeve, by means of these ribs.

The packing member 20 is formed of molded rubber and is securely vulcanized to the sleeve 19. The inner wall or back of the member 20 is of relatively hard rubber and the outer portion thereof is comparatively soft. The upper end of the rubber packing member 20 is cupped as at 23 to provide an upwardly extending peripheral flange of soft rubber so that fluid pressure exerted downwardly against the top of the plunger will cause this flange to be urged outwardly against the inner wall of the barrel, forming a fluid seal.

The sleeve 19 is interiorly threaded to receive the plunger rod 15 at its lower end and to receive a threaded end of the screen 1'7 at its upper end as clearly illustrated in Fig. 2.

The screen 1'1 consists of an elongated hollow tapered member preferably formed of durable metal provided with These slots serve to screen a portion of the fluid that is directed downwardly against the plunger so that the screened fluid will be admitted to the interior of the strainer and thus permitted to flow downwardly through the hollow plunger rod. 15 and escape through ports 25 at the lower end thereof to lubricate the reamer blades.

The plunger above described is very much simpler in construction than plungers heretofore used for this purpose and is very durable, making it particularly suitable for the type of work for which it is intended.

The screen extending upwardly from the plunger, in addition to serving its function as a screen, is of such a size and shape that it provides a convenient wrench by means of which the plunger may be handled during assembly of the device.

packing member is in it is dovetailed thereto spaced slots or ports 24.

In a plunger for an underreamer, an internally threaded sleeve, a flange formed integrallywith said sleeve at the lower endthereof, a rubber packing member molded to said sleeve above said flange, a plunger rod threaded into the lower end of said sleeve, and an elongated tapered fluid strainer threaded into the upper end of the sleeve.

CLARENCE E. BURT. 

